(1) Field of the Invention
The present invention relates to a shield connector to be used when electronic instruments mounted, for example, on a motor vehicle are electrically connected with each other.
(2) Description of the Related Art
Various electronic instruments are mounted on a motor vehicle as a mobile unit. Therefore, the motor vehicle is provided with a wiring harness for transmitting electric power and signals to the electronic instruments. The wiring harness includes a plurality of electric wires and connectors.
The electric wire is so-called a coated electric wire which includes an electrically conductive core wire and a coating, which is made of electrically insulating synthetic resin and coats the core wire. So far, various shield connectors 100 (shown in FIG. 8 as an example) have been used as the connector described above.
The shield connector 100 shown in FIG. 8 is placed on and fixed to a printed circuit board. The shield connector 100 includes an inner housing 101 made of electrically insulating synthetic resin, a terminal fitting 102 attached to the inner housing 101, an inner shield shell 103 made of metal, an outer housing 104 made of electrically insulating synthetic resin, and an outer shield shell 105 made of metal.
The inner housing 101 is formed in a shape of a square tube having one closed end. The terminal fitting 102 is made of metal and formed in a bar-shape. One end part of the terminal fitting 102 is received in the inner housing 101, while another end part thereof is bent at right angles from the one end part and arranged outside the inner housing 101.
The inner shield shell 103 is formed by bending a sheet metal. The inner shield shell 103 receives the inner housing 102 therein and integrally includes: a shell body 106, an inner surface of which is closely placed on an outer surface of the inner housing 102; and a fixing piece 107 which rises up from the shell body 106 and fixed to a conductor pattern of a printed circuit board.
The outer housing 104 is formed in a square tube-shape receiving the inner housing 101 and the inner shield shell 103 therein. The outer shield shell 105 is formed by bending a sheet metal. The outer shield shell 105 receives the outer housing 104 therein and integrally includes: a shell body 108, an inner surface of which is closely placed on an outer surface of the outer housing 104; and a resilient contacting piece 109 which rises up from the shell body 108 inwardly and resiliently comes in contact with the inner shield shell 103.
The shield connector 100 is coupled with a mating connector and guides an electric noise to be leaked to the outside from the terminal fitting 102 and an electric noise to enter the terminal fitting 102 from the outside to a ground circuit by way of the shield shell 103, the outer housing 104, the fixing piece 107 of the shield shell 103, and the conductor pattern of the printed circuit board.
Since the conventional shield connector 100 shown in FIG. 8 includes the inner housing 101 and the outer housing 104, which are covered by the shield shell 103 and the shield shell 105, respectively, therefore as shown in FIG. 9, a gap takes place between the housings 101 and 104, resulting in that a shielding characteristic is hardly secured with the shield shells 103 and 105. That is, the electric noise is hardly prevented from entering the terminal fitting 102 and the electric noise is hardly prevented from leaking from the terminal fitting 102.
Moreover, the outer shield shell 105 is provided with the resilient contacting piece 109 which comes in contact with the inner shield shell 103 and electrically connects the shield shells 103 and 105 to each other. Therefore, the housings 101 and 104 vibrate relatively to each other by vibration of a traveling motor vehicle, resulting in that a contact between the resilient contacting piece 109 and the inner shield shell 103 becomes unstable.